EP0097490B1 - Distanz-/Seiten-/Höbenwinkel-Darstellung eines Schiffes zur Geschützsteuerung - Google Patents
Distanz-/Seiten-/Höbenwinkel-Darstellung eines Schiffes zur Geschützsteuerung Download PDFInfo
- Publication number
- EP0097490B1 EP0097490B1 EP83303482A EP83303482A EP0097490B1 EP 0097490 B1 EP0097490 B1 EP 0097490B1 EP 83303482 A EP83303482 A EP 83303482A EP 83303482 A EP83303482 A EP 83303482A EP 0097490 B1 EP0097490 B1 EP 0097490B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ship
- radar
- sight
- range
- velocity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/66—Radar-tracking systems; Analogous systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/904—SAR modes
- G01S13/9092—SAR modes combined with monopulse techniques
Definitions
- the present invention relates to radar controlled weapons systems and, more particularly, to a method and apparatus for generating real-time high resolution Synthetic Aperture Radar (SAR) imagery from an airborne platform of a translating ship under the influence of roll, pitch, and yaw motions characteristic of sea state conditions.
- SAR Synthetic Aperture Radar
- a highly resolved ship image on an airborne display permits targeting to a particular part of a ship for the purpose of standoff command guidance weapon delivery.
- this invention relates to airborne SAR systems used for generating real-time high resolution imagery of a ship target under the influence of sea state conditions and for accurately measuring and tracking the range and azimuth angle of a designated resolution cell within the aforesaid displayed target area so as to enable the accurate delivery of an air-to-ground missile or glide bomb from the SAR bearing aircraft to the ship target.
- the manner of weapon guidance depends upon reducing to zero the relative range and azimuth angle between weapon and designated target resolution cell.
- the first invention provides an undistorted two-dimensional image of the ship from a direct plot of range versus interferometrically determined azimuth angle of all essential scatterers comprising the ship.
- the second invention provides an improvement in image definition, as well as performance to greater ranges, by displaying range versus doppler, after removal of the isodop type distortions inherent in the formed range/doppler image.
- each of the aforementioned inventions is subject to the limitations on image resolution brought about by the distributed elevation angles of the essential scatterers comprising the ship target.
- US ⁇ A ⁇ 4 321, 601 discloses a SAR method and an apparatus involving motion compensation, range gating and doppler filtering as well interferometric measurements of the elevation angle associated with each range bin and each doppler cell.
- an interferometer antenna comprising two elements spaced in elevation and the signals from these two elements are processed in separate channels, thereby enabling the measurement of the elevation angle from a comparison of the phases in the two channels on a cell by cell basis.
- the prior art also provides centering and focusing functions.
- the invention disclosed herein is related to the inventions described in the aforementioned copending European applications but by a unique processing implementation, is capable of removing any restrictions due to ship scatterer elevation on the formation of a scaled high resolution image. This advantage is brought about by utilizing elevation angle, as well as azimuth angle, interferometric techniques in conjunction with SAR signal processing techniques.
- the object of the present invention may be generally described as providing a method and apparatus for forming, in conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a display, high resolution synthetic aperture radar imagery of a ship target under the influence of sea state conditions.
- the invention is defined in Claim 1.
- a definition of the apparatus according to the invention is provided in Claim 9.
- Aircraft and ship target geometrical and motional relationships which influence the doppler frequencies associated with the signals reflected from the ship target are illustrated in Figure 1.
- the net doppler shift, f d associated with the signal reflected from a scatterer located at azimuth and elevation angle differences, and ⁇ , respectively, with respect to a boresight line-of-sight drawn to the center of ship rotation, considering for the moment, ship translation (without rotation), is given by where V xx , Vyy, and V zz represent the relative line-of-sight and cross line-of-sight velocity components due to both aircraft and ship translations, such that, and where the line-of-sight is drawn to the center of rotation of the ship.
- Equation (5) can be stated, after motion compensation, Without further corrections, a doppler processed ship image would lack display centering in proportion to the error in line-of-sight velocity ⁇ v'xx . As noted in the aforementioned copending application, entitled “Range/doppler Ship Imaging For Ordnance Control", this error source could ordinarily be of considerable magnitude.
- Equation (9) expresses doppler shift in terms of scatterer azimuth and elevation angles, and ⁇ , motion compensation velocity error ⁇ v'xx , and velocities V'yy and V' u , which themselves are functions of ship rotational velocities, W zz and Wyy, and suggests that the three velocity constants could be ascertained from the (over determined) set of measurement points, each one comprised of doppler, azimuth, and elevation angle measurements. To illustrate this, equation (9) is rearranged to read,
- Doppler shift, f' d is related to doppler cell index, i l , after digital signal (Fourier Transform) processing, by where Np is the number of pulses integrated over the synthetic aperture, and f r is the pulse repetition frequency. From equations (10) and (11), It is to be noted that azimuth and elevation angles are determined interferometrically from azimuth and elevation phase shift measurements, ⁇ a and ⁇ e , where and d a and d e are azimuth and elevation interferometer baseline distances, respectively.
- Equation (12) is of the form, where x, y and z denote doppler cell index, azimuth and elevation angles, respectively.
- the three constants, a, b and c are solved for by performing a weighted least squares multivariate regression fit to the body of data, comprised of doppler, azimuth, and elevation angle coordinate values, using formulas from contemporary mathematical art.
- estimates of the three constants, are expressed by, where, x i , y i , z i are the doppler cell index, azimuth, and elevation coordinates of the i th measurement point, and w i is a weighting factor proportional to the variance of each data point, determined by its signal to noise power ratio, a readily measurable quantity.
- Requisite azimuth and elevation angle measurements for the performance of the regression solutions as depicted by Equations (16) through (19) are obtained by reference to Figure 2, which depicts the receiving aperture with four phase centers for azimuth and elevation signal separation.
- Figure 2 depicts the receiving aperture with four phase centers for azimuth and elevation signal separation.
- the sum of signals received at phase centers 2 and 3 are phase compared to the sum of signals received at phase centers 1 and 4 after coherent pulse integration and Fast Fourier Transform (FFT) digital signal processing, to yield in each and every range bin, the azimuth angle of similarly indexed doppler filters, in accordance with Equation (13).
- phase comparison of the sum of signals received at 1 and 2 versus the sum of signals received at 3 and 4 yields elevation angle measurements in accordance with Equation (14), for similarly indexed doppler filters in. each range bin.
- the regression solutions for v'xx , ' yy , and ' zz are used for the formation of the next synthetic aperture.
- the determined error in system line-of-sight velocity v'xx permits a continual (aperture to aperture) update of the system V' xx estimate, thereby eliminating image azimuth centering errors by providing for an exact motion compensation correction for aircraft to ship net line-of-sight velocity.
- the solutions for the net relative rotational velocities as denoted by V'yy and V' zz are used to establish doppler filter bandwidths and frequency separations, as well as the coherent integration time, for the formation of the next aperture of prescribed resolution.
- W' zz and W'yy represent the net relative rotation rates between aircraft and ship derived from the regression solutions for V'yy and ' zz where and and there exists a net instantaneous axis of rotation, W' T , given by, Also, the doppler shift,
- each synthetic aperture permits three scaled image projections with respect to the radar line-of-sight to be viewed on a cathode ray tube display, as illustrated in Figure 4, as an aid to ship identification. These are range/azimuth, elevation/azimuth, and range/elevation image projections.
- elevation angle measurements apt to be less accurate than azimuth angle measurements because of antenna gain or interferometer baseline considerations. Accordingly, considerable benefit can be derived by way of elevation angle accuracy improvement for image display by utilizing the smoothed regression constants and the relatively accurate frequency and azimuth angle measurements. To see this, Equation (12) can be rewritten,
- This elevation smoothing is another feature of the present invention and provides more accurate elevation/azimuth, and range/elevation image projections than would otherwise be obtained on the basis of the actual elevation angle measurements.
- the present invention also has applicability to the technique for producing a range/doppler image of a ship under the influence of sea state conditions, developed by the U.S. Naval Research Laboratory and known as ISAR (Inverse Synthetic Aperture Radar) imaging.
- ISAR Inverse Synthetic Aperture Radar
- the name denotes the fact that SAR doppler resolution stems from predominant target rotation overthat arising from aircraft motion.
- W' T an instantaneous net rotation vector, W' T , lying in the transverse plane to the radar line-of-sight, which determines the doppler frequency of any scatterer location projected onto the transverse plane, such as P', proportional to the distance h, of P' from the W' T axis, in accordance with Equation (26).
- a range/doppler processed (ISAR) image is a representation of a projection along the W' T direction onto the projection plane, as depicted in Figure 5.
- Such a projection provides profile information concerning the ship target in addition to subtended length along the slant range direction and is therefore useful for purposes of ship classification.
- Chip profile is plotted vertically and slant range horizontally, so that ship elevation features plot more closely to the vertical direction on the CRT display). Since W' T is a constantly varying quantity both in magnitude and direction, with a strong dependence upon instantaneous ship rotational motions, observed ISAR imagery undergoes variations in elevation profile as well as image inversions as the sign of W'yy changes.
- ISAR profile imaging has been useful as an aid to ship classification. It is inherently useful to relatively long range because adequate doppler imagery is achievable at modest signal to noise ratios. Due to the ever changing and unpredictable doppler history of any cursored range/doppler cell of the ship for targeting and weapon delivery purposes, however, sustained cursor tracking normally required during a weapon delivery phase is not achievable using ISAR.
- the regression solution for the estimates of W'u and W', and hence the magnitude of the net rotational vector W' T provides the scaling along the doppler sensitive cross-range direction, as denoted by Equation (26). That is, in each range bin, the scaled cross-range displacement, h i , of each scatterer whose doppler shift is (Af),, is found from, and
- Equations (30) and (31) provide for the removal of inversions in displayed imagery to facilitate ship recognition to the extent that such inversions depend upon the sign of W'ri.
- the ISAR projection along the W' T direction can be converted to an equivalent "stretched” projection along the W'yy direction, which would have the further advantage of providing the maximum profile of the ship target as an aid to ship classification.
- the "stretched" profile length, h',, associated with each scatterer, whose measured cross-range location is h i is found from, where, from equations (12) and (15), so that, or
- the so-called “stretched” ISAR plot is displayed in the fourth quadrant of the split screen display depicted in Figure 4, and is virtually the same projection as the range/elevation image projection depicted directly above it.
- the "stretched” projection provides useful quasi-profile imagery for values of ⁇ , (dependent upon relative net rotational vectors W'yy and W'a) between zero and about 60 degrees. For U between 60 and 90 degrees, the "stretched” ISAR image would suffer distortion, so that the scaled (unstretched) projection, more nearly representative of a plan (range/azimuth) projection, is most advantageously plotted.
- the two approaches are used in complementary fashion; the three interferometrically derived range/azimuth, elevation/azimuth, and range/elevation plots provide 3 orthogonal ship image projections with no ship aspect angle sensitivity.
- the "stretched" or “scaled” ISAR projections have aspect sensitivity, with a preference for bow to stern aspect, but provide useful imagery for ship classification to greater ranges due to inherent less noisiness in displayed imagery at the longer ranges.
- Ship translational motion must be tracked so that antenna boresight and range swath start bear a constant relationship with respect to the ship.
- Interferometric azimuth angle data from each useful ship resolution cell are averaged on an array-to-array basis.
- the solution for aircraft to ship relative range rate is tracked so as to advance or retard the range swath start trigger in accordance with ship as well as aircraft motion, so that corresponding ship range increments correspond from pulse-to-pulse.
- range rate and azimuth rate corrections are applied by the system computer so as to also steer antenna boresight in both azimuth and elevation in accordance with both ship and aircraft translational motions.
- a high resolution range/azimuth ship image permits the placement of a cursor at the location within the image of a particular resolution cell constituting the designated target cell.
- To carry out command weapon guidance to its ultimate accuracy capability requires that the cursor location be tracked through a succession of images so as to be continuously superimposed over the initially designated resolution cell since the weapon is targeted to the cursor location.
- cursor tracking of a designated target cell is accomplished in terms of its predicted range/azimuth location reference to the SAR bearing aircraft on the basis of the derived relative translation between aircraft and ship from aperture to aperture, on the basis of the regression solution for line-of-sight velocity, denoted by v'xx .
- the range and azimuth distance corrections dy and dx, respectively, to be applied to the cursor coordinate locations are, and where x and y are the initial cursor azimuth and range locations, and dt represents the time increment from initial cursor placement.
- FIG. 7 a block diagram of the preferred embodiment of the system utilized for practicing the present invention is illustrated.
- pulses of electromagnetic energy generated in a Coherent Transmitter 11 from reference signals derived in an Exciter/Frequency Synthesizer 12 are radiated from a Transmitting Antenna 9 so as to optimally illuminate a ship target under way on the surface of the sea.
- Signals reflected from the ship target are received by an Interferometer Antenna 10 comprised of four separate receiving elements whose common boresight direction corresponds to that of the Transmitting Antenna 9.
- Switching signals at the system pulse repetition frequency generated in a General Purpose Computer 17 are applied to an Azimuth And Elevation Array Switching Unit 8 for the purpose of combining signals received by the four antenna apertures so as to form interleaved azimuth and elevation signal pairs through two receiver channels (Receivers 13 and 14) for subsequent interferometric angle processing.
- the signals from antenna arrays 1 and 2 are coherently added on a microwave hybrid summing network located in the Azimuth and Elevation Array Switching Unit 8, as are the signals from antenna Arrays 3 and 4, after which the two sums are separately inputted to the Receivers 13 and 14, respectively, representing inputs to two separate synthetic arrays for elevation interferometric phase comparison.
- signals from antenna arrays 1 and 4 as well as arrays 2 and 3 are separately added and inputted to the Receivers 13 and 14, representing inputs to two separate synthetic arrays for azimuth interferometric phase comparison.
- These analog signal components are digitzed in A/D Converters 15 and 16 at a sampling rate determined by system range resolution requirements.
- These digitized samples are alternately sorted out on a pulse-to-pulse basis and are stored in a Bulk Memory 19 for the subsequent processing of 4 range/doppler matrices, two of which are requisite for elevation angle determination on a cell by cell basis, and two for azimuth.
- motion compensation corrections for antenna phase center translational and rotational motions, as well as for ship translational motion are computed and stored in a Motion Compensation Unit 20 in a time sequenced order on the basis of computations performed in the General Purpose Computer 17 of the two-way line-of-sight displacement change between antenna phase centers and the tracking center-of- gravity of the ship, predicated on the regression solution obtained for the line-of-sight velocity error, e V l xx , performed in a Velocity Computer 27.
- corrections stored in the Motion Compensation Unit 20 are applied to the time sequences stored in the Bulk Memory 19 in the form of vector rotations reflecting the two-way motion compensation phase correction to each range sample of each pulse of the four sequences stored in the Bulk Memory 19.
- data is read out of the Bulk Memory 19 (as new data is being entered) for Fourier Transform digital signal processing to produce the necessary filtering so as to provide the desired resolution along the doppler sensitive direction and in each range bin in accordance with Equations 25 and 26, wherein the solutions for V'yy and V'zz are obtained from General Purpose Computer 17.
- the filtering is performed in FFT Processors 21 to 24 which perform Fast Fourier Transform digital processing so as to produce doppler resolved coherently integrated vector sums in each filter of each range bin.
- the processed outputs of FFT Processors 21 to 24 are seen to represent range/doppler resolved vectors representing, respectively, the net signal power in the upper (Arrays 1 and 2), lower (Arrays 3 and 4), left (Arrays 1 and 4) and right (Arrays 2 and 3) antenna sections throughout their respective sampled intervals.
- Range/Azimuth Map Generator 26 which produces the interferometric spatial azimuth angle , associated with each resolved range/doppler cell, in accordance with where d a and ⁇ a are azimuth interferometer baseline length, and measured electrical phase of each resolution cell, respectively.
- the range/doppler/elevation angle coordinates from the Range/Elevation Map Generator 25 and the range/doppler/azimuth angle coordinates form the Range/azimuth Map Generator 26 (for each range/ doppler resolved cell) are red into the Velocity Computer 27 where a weighted multivariate regression solution, using doppler, elevation, and azimuth angle variables, is performed for the regression constants, ⁇ , b and in accordance with Equations (16) to (19), from which the velocity constants, v'xx , V ' yy and ' zz , as specified by Equations (20) to (22), are computed in the General Purpose Computer 17.
- the weight w, applied to each coordinate, x,, y, and z entering the regression solutions, are read into the Velocity Computer 27 from either of the FFT Processors 21-24 through either the Range/Elevation Map Generator 25 or the Range/Azimuth Map Generator 26.
- the values of A, f r , and Np used in the evaluation of Equations (20) through (22) are operating constants available in General Purpose Computer 17, where f, represents the pulse repetition frequency governing the formation of the interleaved azimuth and elevation synthetic apertures, each of which occurs at one half the pulse repetition frequency at which pulses are transmitted.
- the regression solution for v'xx in General Purpose Computer 17 serves as a correction of - v'xx to the line-of-sight velocity estimate.
- Updated line-of-sight velocity is applied to the Motion Compensation Unit 20 which applies motion compensation phase corrections to data stored in the Bulk Memory 19 for the purpose of image focusing and to drive the residual doppler in the boresight direction, assumed centered at the center of rotation of the ship, to zero, so as to avoid possible doppler foldovers which could have a disturbing influence on the doppler/azimuth/elevation coordinate data provided to the Velocity Computer 27 for regression analysis.
- the remaining two velocity estimates, V'yy and ' zz are used in General Purpose Computer 17 to compute doppler bandwidth, BW, and integration time, T, for the formation of the next aperture, in accordance with Equations (27) and (28), so as to achieve a prescribed resolution of d res along the doppler sensitive direction, where the slant range, R o in Equation (27) is known in the General Purpose Computer 17 on the basis of inputs from an Interial Navigation System 18.
- the system pulse repetition frequency is twice f, due to manner in which the elevation and azimuth arrays are interleaved).
- Azimuth and elevation angle data is scaled directly in feet along their respective directions in the Velocity Computer 27 by multiplying by slant range, R o , obtained from the General Purpose Computer 17.
- Three sets of coordinate data depicting the locations of ship scatterers are transferred from the Velocity Computer 27 to a Scan Converter 28 for display on a split screen divided into four quadrants in a CRT Display 29. These are the range/azimuth, azimuth/elevation, and range/elevation coordinate values, representing the three orthogonal image projections of the ship target.
- a representation of such image projections for a hypothetical ship target is shown in Figure 4.
- interferometric angle measurements start to become noise because of angle glint errors accompanying such measurements arising from normal receiver thermal noise limitations for fixed transmitter and antenna parameters. Due to aperture restrictions governing elevation angle measurement accuracy in the system cited herein, elevation locational errors in displayed imagery at long range due to such expected measurement noise are substantially reduced.
- the system range capability for displaying useful imagery can be materially extended by solving for smoothed elevation locational values on the basis of the equation governing the interrelationships of spacial angles, doppler frequency, and regression constants, stated by equation (29), as By substituting the values of regression constants, ⁇ , band , and the relatively accurate values of doppler cell index, i,, and azimuth angle, of each coordinate point into Equation 29, a smoothed value, ⁇ is obtained for each such coordinate point.
- the smoothed elevation values, ⁇ , derived in this manner in the Velocity Computer 27, are read into the Scan Converter 28, to produce displayed images in the azimuth/elevation and range/elevation image projections of considerable greater accuracy than those that would have been produced by displaying the original elevation measurements themselves.
- Antenna azimuth steering commands are generated in the General Purpose Computer 17 on the basis of aircraft navigational data inputs from the Inertial Navigation System 18 and averaged interferometric azimuth angle measurements from the various ship scatterers provided by the Range/Azimuth Map Generator 26, in such a manner as to maintain the average of all interferometric azimuth angles at zero (with respect to its electrical boresight) when smoothed with a tracking filter in the General Purpose Computer 17 over successive apertures.
- the net pulse-to-pulse two-way line-of-sight displacement change due to relative translation motion between aircraft and ship computed in the General Purpose Computer 17 for purposes of motion compensation also serves as a basis for controlling the precise timing for the start of range sampling at the A/D Converters 15 and 16, so that corresponding samples from pulse-to-pulse over the coherent integration interval represent the same range increment of the ship.
- the net-line-of-sight displacement change with time, in conjunction with aircraft altitude available in the General Purpose Computer 17 from other on-board sensors, is used to provide elevation steering to the transmitting and receiving Interferometer Antennas 9 and 10.
- Cursor placement to a desired range/azimuth resolution cell of the ship image is achieved by operator designation of video signals through the General Purpose Computer 17 and applied to the Scan Converter 28. Cursor tracking of the designated ship target resolution cell during the weapon delivery phase is similarly controlled by the General Purpose Computer 17 on the basis of its computations of target cell range and azimuth angle change with time derived from its navigational solutions for translational motions between aircraft and ship, wherein said cursor video signals are injected into appropriate range/azimuth resolution cells as time progresses.
- Second order corrections to cursor tracking of the designated ship target cell to eliminate potential tracking errors arising from ship rotational (yaw) motion are effected as previously described in the aforementioned co-pending application, entitled "Range/Azimuth Angle Ship Imaging For Ordnance Control".
- the range/azimuth/elevation coordinates of the targeted part of the ship for standoff command guidance weapon delivery is indicated by the cursor location which is tracked in the General Purpose Computer 17.
- Control signals for the pointing of the Antennae 9 and 10 and for pulse repetition frequency (prf) control of the coherent Transmitter 11 are obtained from the General Purpose Computer 17. All task management such as data transmission and initiation of subroutine sequences, are performed by a Radar Data Processor 30.
- the useful range of the system can be extended by smoothing the derived velocities iv, V' yy and V, zz using state-of-the-art curve fitting techniques to such data derived over multiple apertures, implemented in the General Purpose Computer 17.
Claims (16)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/389,369 US4546355A (en) | 1982-06-17 | 1982-06-17 | Range/azimuth/elevation ship imaging for ordnance control |
US389369 | 1982-06-17 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0097490A2 EP0097490A2 (de) | 1984-01-04 |
EP0097490A3 EP0097490A3 (en) | 1984-09-05 |
EP0097490B1 true EP0097490B1 (de) | 1989-05-10 |
Family
ID=23537982
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83303482A Expired EP0097490B1 (de) | 1982-06-17 | 1983-06-16 | Distanz-/Seiten-/Höbenwinkel-Darstellung eines Schiffes zur Geschützsteuerung |
Country Status (9)
Country | Link |
---|---|
US (1) | US4546355A (de) |
EP (1) | EP0097490B1 (de) |
JP (1) | JPS5927281A (de) |
AU (1) | AU562285B2 (de) |
CA (1) | CA1212166A (de) |
DE (1) | DE3379847D1 (de) |
GR (1) | GR78287B (de) |
IL (1) | IL68374A (de) |
NO (1) | NO164743C (de) |
Families Citing this family (67)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2315944B (en) * | 1979-05-16 | 1998-06-24 | British Aerospace | Improvements relating to surveillance apparatus |
US4771287A (en) * | 1983-06-23 | 1988-09-13 | Westinghouse Electric Corp. | Method of correcting for errors in radar imaging |
JPS60249074A (ja) * | 1984-05-24 | 1985-12-09 | Fujitsu Ltd | 飛翔体航跡推定方式 |
JPS61138188A (ja) * | 1984-12-10 | 1986-06-25 | Toshiba Corp | レ−ダ装置 |
US4630051A (en) * | 1985-03-01 | 1986-12-16 | Holodyne Ltd., 1986 | Imaging doppler interferometer |
AU632280B2 (en) * | 1985-07-02 | 1992-12-24 | Gec-Marconi Limited | A synthetic aperture radar |
US4723124A (en) * | 1986-03-21 | 1988-02-02 | Grumman Aerospace Corporation | Extended SAR imaging capability for ship classification |
GB2241131B (en) * | 1986-07-30 | 1991-11-27 | Thorn Emi Electronics Ltd | Radar |
JPH0693029B2 (ja) * | 1986-08-20 | 1994-11-16 | 三菱電機株式会社 | レ−ダ装置 |
US4855747A (en) * | 1987-08-17 | 1989-08-08 | Trustees Of The University Of Pennsylvania | Method of target imaging and identification |
US4829306A (en) * | 1987-08-31 | 1989-05-09 | Norges Teknisk-Naturvitenskapelige Forskningsråd | System for detection of objects with given, known characteristics against a background |
US6930633B1 (en) * | 1988-03-22 | 2005-08-16 | Raytheon Company | Adaptive glint reduction method and system |
US5610610A (en) * | 1988-05-18 | 1997-03-11 | Hughes Electronics | Inverse synthetic array radar system and method |
US4829303A (en) * | 1988-05-18 | 1989-05-09 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Data volume reduction for imaging radar polarimetry |
US5016018A (en) * | 1989-03-22 | 1991-05-14 | Hughes Aircraft Company | Aperture synthesized radiometer using digital beamforming techniques |
US4885590A (en) * | 1989-04-14 | 1989-12-05 | General Electric Company | Blind speed elimination for dual displaced phase center antenna radar processor mounted on a moving platform |
IT1231358B (it) * | 1989-04-21 | 1991-12-02 | Selenia Ind Elettroniche | Dispositivo per migliorare la risoluzione radar |
GB2256765B (en) * | 1989-11-28 | 1994-01-05 | Marconi Gec Ltd | Synthetic aperture imaging apparatus |
US5132693A (en) * | 1990-05-31 | 1992-07-21 | The Boeing Company | Radar apparatus |
US5160931A (en) * | 1991-09-19 | 1992-11-03 | Environmental Research Institute Of Michigan | Interferometric synthetic aperture detection of sparse non-surface objects |
US5189424A (en) * | 1991-09-19 | 1993-02-23 | Environmental Research Institute Of Michigan | Three dimensional interferometric synthetic aperture radar terrain mapping employing altitude measurement and second order correction |
US5170171A (en) * | 1991-09-19 | 1992-12-08 | Environmental Research Institute Of Michigan | Three dimensional interferometric synthetic aperture radar terrain mapping employing altitude measurement |
US5184133A (en) * | 1991-11-26 | 1993-02-02 | Texas Instruments Incorporated | ISAR imaging radar system |
US5281972A (en) * | 1992-09-24 | 1994-01-25 | Hughes Aircraft Company | Beam summing apparatus for RCS measurements of large targets |
EP0634669B1 (de) * | 1993-07-15 | 1997-09-24 | Daimler-Benz Aerospace Aktiengesellschaft | Verfahren zur Klassifikation eines Gegenstandes und Verwendung des Verfahrens |
US5442364A (en) * | 1993-07-22 | 1995-08-15 | The United States Of America As Represented By The Secretary Of The Navy | Alignment and beam spreading for ground radial airborne radar |
US5343204A (en) * | 1993-07-29 | 1994-08-30 | Unisys Corporation | Auto-focusing correction for rotational acceleration effects on inverse synthetic aperture radar images |
US5467092A (en) * | 1994-05-31 | 1995-11-14 | Alliedsignal Inc. | Radar system including stabilization calibration arrangement |
US5424743A (en) * | 1994-06-01 | 1995-06-13 | U.S. Department Of Energy | 2-D weighted least-squares phase unwrapping |
US5784166A (en) * | 1996-04-03 | 1998-07-21 | Nikon Corporation | Position resolution of an interferometrially controlled moving stage by regression analysis |
US5673050A (en) * | 1996-06-14 | 1997-09-30 | Moussally; George | Three-dimensional underground imaging radar system |
US5874918A (en) * | 1996-10-07 | 1999-02-23 | Lockheed Martin Corporation | Doppler triangulation transmitter location system |
US5835060A (en) * | 1996-10-07 | 1998-11-10 | Lockheed Martin Corporation | Self-resolving LBI triangulation |
FR2756052B1 (fr) * | 1996-11-19 | 1999-02-05 | Thomson Csf | Procede de determination des parametres du mouvement propre d'un objet mobile pour radar coherent et application a un procede d'imagerie coherente |
US7952511B1 (en) * | 1999-04-07 | 2011-05-31 | Geer James L | Method and apparatus for the detection of objects using electromagnetic wave attenuation patterns |
JP3832139B2 (ja) * | 1999-05-17 | 2006-10-11 | 三菱電機株式会社 | レーダ信号処理器 |
US6329945B1 (en) * | 2000-04-20 | 2001-12-11 | Novatel, Inc. | System for improved GPS accuracy using a sky map |
JP2004535043A (ja) | 2001-07-13 | 2004-11-18 | シファーゲン バイオシステムズ, インコーポレイテッド | 時間依存デジタル信号の信号スケーリングプロセス |
IL154396A0 (de) * | 2002-12-29 | 2009-02-11 | Haim Niv | |
JP4392661B2 (ja) * | 2003-01-16 | 2010-01-06 | 東レ・ファインケミカル株式会社 | 光学活性ジアシル酒石酸の回収方法 |
US7725151B2 (en) * | 2003-06-02 | 2010-05-25 | Van Der Weide Daniel Warren | Apparatus and method for near-field imaging of tissue |
US7362268B2 (en) * | 2005-05-11 | 2008-04-22 | Qualcomm Inc | Method for detecting navigation beacon signals using two antennas or equivalent thereof |
US20080079625A1 (en) * | 2006-10-03 | 2008-04-03 | William Weems | System and method for stereoscopic anomaly detection using microwave imaging |
EP2100255A4 (de) * | 2006-12-06 | 2013-12-04 | Kirsen Technologies Corp | System und verfahren zur erkennung gefährlicher objekte und stoffe |
US7598900B2 (en) * | 2007-11-09 | 2009-10-06 | The Boeing Company | Multi-spot inverse synthetic aperture radar imaging |
US8400875B2 (en) * | 2010-04-06 | 2013-03-19 | Raytheon Company | Active sonar system and active sonar method using a pulse sorting transform |
KR101138292B1 (ko) * | 2010-05-18 | 2012-04-24 | 국방과학연구소 | 전방관측 3차원 영상 레이더 장치 및 그를 이용한 3차원 영상 획득방법 |
JP5979868B2 (ja) * | 2011-12-21 | 2016-08-31 | 三菱電機株式会社 | 画像レーダ装置 |
DE102012207186A1 (de) * | 2012-03-29 | 2013-10-02 | Rohde & Schwarz Gmbh & Co. Kg | Verfahren und Vorrichtung zur Detektion von Strukturen in einem zu untersuchenden Objekt |
CN104297750B (zh) * | 2014-09-25 | 2017-03-15 | 南京航空航天大学 | 基于几何投影的双基前视sar成像面预测方法 |
JP6413588B2 (ja) * | 2014-10-08 | 2018-10-31 | 三菱電機株式会社 | 誘導装置 |
US11262447B2 (en) * | 2017-02-24 | 2022-03-01 | Japan Aerospace Exploration Agency | Flying body and program |
GB2566667B (en) * | 2017-06-07 | 2022-05-25 | Wrekin Holdings Ltd | Ground surface access cover assemblies |
US10613212B2 (en) | 2017-08-14 | 2020-04-07 | Oculii Corp. | Systems and methods for doppler-enhanced radar tracking |
US10564277B2 (en) | 2018-01-30 | 2020-02-18 | Oculii Corp. | Systems and methods for interpolated virtual aperature radar tracking |
US11428782B2 (en) * | 2019-05-02 | 2022-08-30 | GM Global Technology Operations LLC | Neural network-based object surface estimation in radar system |
CN110658520B (zh) * | 2019-08-19 | 2021-10-29 | 中国科学院电子学研究所 | 一种合成孔径雷达成像系统及方法 |
US11047974B1 (en) | 2019-12-13 | 2021-06-29 | Oculii Corp. | Systems and methods for virtual doppler and/or aperture enhancement |
US11041940B1 (en) | 2019-12-20 | 2021-06-22 | Oculii Corp. | Systems and methods for phase-modulated radar detection |
KR20210082946A (ko) * | 2019-12-26 | 2021-07-06 | 삼성전자주식회사 | 레이더 신호 처리 장치 및 방법 |
US11280879B2 (en) | 2020-06-16 | 2022-03-22 | Oculii Corp. | System and method for radar interference mitigation |
US11846700B2 (en) * | 2020-10-01 | 2023-12-19 | Texas Instruments Incorporated | On-field phase calibration |
US11841420B2 (en) | 2020-11-16 | 2023-12-12 | Oculii Corp. | System and method for radar-based localization and/or mapping |
FR3117246B1 (fr) * | 2020-12-09 | 2022-11-25 | Mbda France | Procédé et dispositif pour générer un nuage 3D optimisé de points d'un objet longiforme à partir d'images générées par un radar à synthèse d'ouverture multivoies. |
CN113406631B (zh) * | 2021-05-14 | 2024-02-23 | 中山大学 | 一种自旋空间目标姿态估计方法、系统、装置及存储介质 |
CN113589284B (zh) * | 2021-07-28 | 2023-12-22 | 河南大学 | 一种逆合成孔径雷达对舰船目标的成像方法和系统 |
US11561299B1 (en) | 2022-06-03 | 2023-01-24 | Oculii Corp. | System and method for multi-waveform radar tracking |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2996706A (en) * | 1953-05-29 | 1961-08-15 | Sperry Rand Corp | Apparatus for computing and predicting varying conditions for aircraft guidance in landing on floating decks |
US3453619A (en) * | 1967-10-23 | 1969-07-01 | Defence Canada | Sea motion corrector |
US3733603A (en) * | 1968-07-31 | 1973-05-15 | Us Army | Radar target identification system |
US3610901A (en) * | 1969-09-09 | 1971-10-05 | Emerson Electric Co | Digital modified discrete fourier transform doppler radar processor |
US4321601A (en) * | 1971-04-23 | 1982-03-23 | United Technologies Corporation | Three dimensional, azimuth-correcting mapping radar |
US3806929A (en) * | 1971-06-24 | 1974-04-23 | Us Navy | Method for the detection of radar targets |
US4170006A (en) * | 1971-08-30 | 1979-10-02 | United Technologies Corporation | Radar speed measurement from range determined by focus |
US3735400A (en) * | 1971-11-23 | 1973-05-22 | Us Air Force | Amti radar clutter cancelling method and apparatus |
US3798425A (en) * | 1972-08-29 | 1974-03-19 | Hughes Aircraft Co | Target motion compensator |
US3987442A (en) * | 1974-06-24 | 1976-10-19 | Raytheon Company | Digital MTI radar system |
US3983558A (en) * | 1974-06-28 | 1976-09-28 | The United States Of America As Represented By The Secretary Of The Army | Moving target indicating (MTI) radar systems employing vehicle discriminator apparatus |
US4086590A (en) * | 1975-03-27 | 1978-04-25 | The United States Of America As Represented By The Secretary Of The Air Force | Method and apparatus for improving the slowly moving target detection capability of an AMTI synthetic aperture radar |
FR2315703A1 (fr) * | 1975-06-24 | 1977-01-21 | Thomson Csf | Systeme radar a vision laterale |
US3993994A (en) * | 1975-06-27 | 1976-11-23 | The United States Of America As Represented By The Secretary Of The Air Force | Adaptive clutter cancellation for synthetic aperture AMTI radar |
US3987440A (en) * | 1975-07-16 | 1976-10-19 | United Technologies Corporation | Track while scan operation on scintillating point targets |
FR2341142A1 (fr) * | 1976-02-10 | 1977-09-09 | Labo Cent Telecommunicat | Dispositif de reconnaissance automatique des engins a chenilles |
US4068231A (en) * | 1976-09-02 | 1978-01-10 | Hughes Aircraft Company | Automatic clutter-mapper |
US4101891A (en) * | 1976-11-24 | 1978-07-18 | Nasa | Surface roughness measuring system |
US4084158A (en) * | 1977-01-03 | 1978-04-11 | Raytheon Company | Method of operating synthetic aperture radar |
US4134113A (en) * | 1977-04-18 | 1979-01-09 | Westinghouse Electric Corporation | Monopulse motion compensation for a synthetic aperture radar |
JPS56100372A (en) * | 1979-12-28 | 1981-08-12 | Ibm | Movinggtarget detector |
US4549184A (en) * | 1981-06-09 | 1985-10-22 | Grumman Aerospace Corporation | Moving target ordnance control |
-
1982
- 1982-06-17 US US06/389,369 patent/US4546355A/en not_active Expired - Fee Related
-
1983
- 1983-04-13 IL IL68374A patent/IL68374A/xx not_active IP Right Cessation
- 1983-04-15 AU AU13567/83A patent/AU562285B2/en not_active Ceased
- 1983-05-09 CA CA000427755A patent/CA1212166A/en not_active Expired
- 1983-06-13 GR GR71644A patent/GR78287B/el unknown
- 1983-06-16 EP EP83303482A patent/EP0097490B1/de not_active Expired
- 1983-06-16 DE DE8383303482T patent/DE3379847D1/de not_active Expired
- 1983-06-16 NO NO832193A patent/NO164743C/no unknown
- 1983-06-17 JP JP58110031A patent/JPS5927281A/ja active Granted
Also Published As
Publication number | Publication date |
---|---|
JPH045157B2 (de) | 1992-01-30 |
GR78287B (de) | 1984-09-26 |
IL68374A (en) | 1987-10-30 |
AU1356783A (en) | 1983-12-22 |
JPS5927281A (ja) | 1984-02-13 |
NO832193L (no) | 1983-12-19 |
AU562285B2 (en) | 1987-06-04 |
NO164743C (no) | 1990-11-07 |
DE3379847D1 (en) | 1989-06-15 |
CA1212166A (en) | 1986-09-30 |
US4546355A (en) | 1985-10-08 |
EP0097490A3 (en) | 1984-09-05 |
NO164743B (no) | 1990-07-30 |
EP0097490A2 (de) | 1984-01-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0097490B1 (de) | Distanz-/Seiten-/Höbenwinkel-Darstellung eines Schiffes zur Geschützsteuerung | |
US4723124A (en) | Extended SAR imaging capability for ship classification | |
EP0100141B1 (de) | Distanz-/Doppler-Darstellung eines Schiffes zur Geschützsteuerung | |
EP0097491B1 (de) | Distanz-/Seitenwinkel-Darstellung eines Schiffes zur Geschützsteuerung | |
EP0093603B1 (de) | Feuerleiteinrichtung für bewegliche Ziele | |
CA1083695A (en) | Method of operating synthetic aperture radar | |
US7196653B2 (en) | Imaging apparatus and method | |
US4825213A (en) | Simultaneous triple aperture radar | |
US20030214431A1 (en) | Methods and apparatus for determination of a filter center frequency | |
CN113687356B (zh) | 一种机载多通道圆迹sar运动目标检测与估计方法 | |
CN113238226B (zh) | 一种合成孔径雷达 | |
US20030210177A1 (en) | Methods and apparatus for determining an interferometric angle to a target in body coordinates | |
US6680691B2 (en) | Methods and apparatus for accurate phase detection | |
CN115792907B (zh) | 星载sar斜视滑动聚束模式方位向成像参数设计方法 | |
US6674397B2 (en) | Methods and apparatus for minimum computation phase demodulation | |
US6734820B2 (en) | Methods and apparatus for conversion of radar return data | |
CN108732555B (zh) | 一种自动驾驶阵列微波成像运动补偿的方法 | |
US6639545B1 (en) | Methods and apparatus to determine a target location in body coordinates | |
Nie et al. | A quadtree beam-segmenting based wide-swath SAR polar format algorithm | |
Azouz et al. | New SAR Algorithm for Sidelobe Reduction in Range direction | |
RU2801361C1 (ru) | Способ формирования радиолокационных изображений в рлс с синтезированной апертурой антенны | |
Xia et al. | Real-time Imaging Algorithm for High-Squint Maneuvering-Platform SAR | |
Deng et al. | Calibration of Antennas Phase Imbalance of an FMCW ATI-SAR for Surface Velocity Mapping | |
Leung et al. | Processing of scan SAR mode data for Radarsat | |
HENG et al. | Precision focusing algorithms for spaceborne Synthetic Aperture Radar (SAR) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): DE FR GB IT NL SE |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Designated state(s): DE FR GB IT NL SE |
|
17P | Request for examination filed |
Effective date: 19850129 |
|
17Q | First examination report despatched |
Effective date: 19870202 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR GB IT NL SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Effective date: 19890510 Ref country code: NL Effective date: 19890510 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 19890612 Year of fee payment: 7 |
|
REF | Corresponds to: |
Ref document number: 3379847 Country of ref document: DE Date of ref document: 19890615 |
|
ET | Fr: translation filed | ||
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 19890630 Year of fee payment: 7 |
|
ITF | It: translation for a ep patent filed |
Owner name: MODIANO & ASSOCIATI S.R.L. |
|
NLV1 | Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
ITTA | It: last paid annual fee | ||
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 19930604 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19930609 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19930630 Year of fee payment: 11 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Effective date: 19940616 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 19940616 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19950228 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Effective date: 19950301 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |